GLAND STRUCTURES. 79 



deprived of its acini, which are broken away by the 

 least violence. 



Systems No. 2 and No. 3 are intercellular, like the 

 spinning gland, whence they are derived — i.e., the cells 

 are arranged around a cavity, towards which they pre- 

 sent their secreting surfaces, while they absorb material 

 from the blood by that portion lying next the propria 

 (a, C, Fig. 16). The secretion passes forwards in a 

 manner made obvious by the illustration. When the 

 several ducts begin to unite, they develop an interior 

 spiral thread like to that of the tracheae, both in 

 purpose (page 34) and appearance. Their presence 

 led Fischer to suppose these glands to be lungs. In 

 System No. 3 these threads are especially strong, as 

 indicated at a A, d D. They pour their contents into 

 a sac {sc, A), curiously covered by star-shaped plates. 

 The ducts of both systems uniting, as previously 

 described, form a single channel, passing onwards 

 through the mentum (mt, Fig. 18), or chin, into the 

 tongue, where it terminates in a salivary valve (sv, A, 

 Fig. 18), from which the saliva is pumped out during 

 the action of sucking, an operation which may be 

 artificially performed after the death of the bee. 



System No. 4 of Schiemenz, or the olfactory gland 

 {Riechschleimdrilse) of Wolff* (og, Fig. 10), closely 

 resembles No. 1 in its minute structure, being intra- 

 cellular, and, in consequence, very active. It has its 

 aperture immediately within the mandible, is singu- 

 larly large in the queen, smaller in the worker, and 

 still less in the drone. 



* "Nova Acta Acedemia Naturae Curiosorum," vol. xxxviii., "Das 

 Riechorgan der Biene," Dr. O. J. B. Wolff. 



